Chemical, cosmetic, personal care, pharmaceutical, and consumable products must be safe for consumers and some must comply with government regulations. Therefore, manufacturers of these products must test the products for any contamination with incoming raw materials during the manufacturing process and prior to shipping the finished products to wholesale and/or retail and pharmacy outlets for sale. While testing is in progress, the products are held in warehouses or other storage facilities until testing is completed and the products are cleared for shipment. The time required to hold the products while testing for contaminants is known as “micro-hold time,” and can cause companies to accrue significant costs relating to warehousing of the products and time lost before the products can be sold and delivered to consumers. Any method that simplifies, accelerates the means of contamination detection, or increases its sensitivity would interest manufacturers. Novel methods of achieving a faster turnaround in obtaining test results in microbiology are typically referred to as “rapid methods.”
One current approach to rapid method development in microbiology is to develop and identify methods for detecting molecules that are usually present in all microbial cells, so-called “marker molecules.” These marker molecules include, but are not limited to adenylate kinase (AK), alkaline phosphatase (AP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP). These markers can be detected using chemiluminescence, bioluminescence, and other methods. Detection of these marker molecules in a sample can indicate the presence of contaminating microbial cells not only very rapidly, but often with more sensitivity than older, conventional methods. However, oftentimes products to be tested may initially contain a very low number of contaminating microbial cells, and therefore those products have low, even undetectable concentrations of the marker molecules.
Some consumer products, or samples, tested for contamination often require a period of incubation before an analyst can perform a detection assay. Incubation in this case refers broadly to encouraging the growth of contaminating microorganisms in a sample by providing conditions for contamination growth, such as water, nutrients, or a warm environment. Some product types, for example, milk or orange juice, contain sufficient water and nutrients for growth. Merely incubating such product types at a warm temperature is enough to encourage the growth of contaminating microorganisms to rapidly detectable levels. Since products like these are typically supplied in bottles or cartons, the entire bottle or carton is usually incubated intact for convenience before sampling for microbial contamination.
By comparison, other product types, such as household, personal care or pharmaceutical products, are inherently low in water or nutrients. To encourage the growth of any microorganisms within these product types, they must first be dissolved or suspended in a volume of nutrient broth or other appropriate liquid before incubating them at a warm temperature. An example of a typical sample dilution would be the suspension of 1 g product in a volume of 100 ml nutrient broth or other diluent.
Presently, most “rapid detection” methods for determining the presence or absence of microorganisms in chemical, cosmetic, personal care, pharmaceutical, and consumable products can take up to 24 hours, or even longer. A need exists for more rapid methods of detecting microorganisms that can be completed in less than 8 hours, e.g., about 6 hours to about 8 hours, and decrease the so-called micro-hold time are needed. An additional need exists for rapid methods that greatly reduce any factors that might inhibit the detection of microorganisms, yet increase overall detection sensitivity.